necklace that stretches round Cecilia Gallerani’s
throat and down her chest to her bosom.
“Obviously, some of the necklace beads are not
by Leonardo”, Mr Cotte asserts. He increases the
magnification – and lo and behold, we can all see
that whereas some of those beads have exquisite
definition and shape, others have been executed
very clumsily, almost to the point where they are
mere blobs of black paint.
From Alasdair Palmer
Public Policy Editor,
The Sunday Telegraph
SUNDAY MARCH 16th 2008
THE CAMERA WHO CHANGES ART FOR
EVER
WHAT LIES BENEITH
Are art restorers unwittingly ruining the
paintings they're trying to preserve?
The inventor of a powerful new camera capable of picking out Leonardo's
thumbprint among the brushstrokes thinks so. Alasdair Palmer meets the man
breathing new life into Old Masters
“It’s a revelation!”, Mike Daley exclaims. An artist
and historian of art restoration, he is asthonished
by the reproduction on the giant screen in front of
him.
‘It’ is a recently-developed digital camera whose
primary use is to produce images of Old Master
paintings. I can testify that its results are every bit
as astonishing as Mr Daley’s amazed reaction
suggests. The reproduction is so accurate and
the resolution so high that it is possible to
magnify an image of the surface of a picture to
produce details that no-one has ever seen
before, and no-one suspected were there.
Mr Daley and I are in the office of Lumiere
Technology in the Boulevard St Germain in Paris.
Pascal Cotte, the camera’s inventor, is
demonstrating its powers. We’re looking at an
image of Leonardo Da Vinci’s wonderful picture
The Lady with the Ermine. The sitter was
probably Cecilia Gallerani, who was only 16 or 17
when her portrait was painted; she was also the
mistress of Ludovico Sforza, the Duke of Milan,
then employing Leonardo on a variety of projects,
the least important of which involved him in
painting something. Mr Cotte focuses in on the
Leonardo da Vinci's 'Lady with an Ermine': the digital
image (right) shows that the original background was
blue, not black.
Below: Leonardo’s thumbprint, as revealed on the
painting
“Leonardo would never have done that”,
comments Jacques Franck, who is also in the
audience. Mr Franck is probably the world’s
greatest expert on Leonardo’s technique. He has
done what no-one else has managed to: he has
himself painted copies of Leonardo’s pictures
which are almost indistinguishable from the
originals, using the technique he believes
Leonardo employed.
“But just take a look at this!”, says Mr Cotte. An
ebullient father of five, he has just turned 50 -- but
he looks about twenty years younger. He
increases the magnification higher still, and we
investigate the delicate contours of the depiction
of the exposed flesh between Cecilia Gallerani’s
neck and the start of her dress. We all gasp as
we start to see, in unprecedented close-up, the
subtlety of Leonardo’s sfumato technique, which
models the undulations of the surface of her skin
by a series of almost imperceptible changes of
colour and tone. As the magnification increases,
the brush strokes begin to be visible -- but they
are so fine, and they blend together so perfectly,
that even at this level of magnification, they are
very difficult to discern.
Lumiere Technology – Press Release Sunday March 16th 2008
Jean Penicaut & Pascal Cotte are at Tefaf Maastricht – Stand 527 Business Pavillon
1
Someone starts to rhapsodise about the marvels
of Leonardo’s technique. “No, not the sfumato!”
Mr Cotte interrupts. “I mean this!” He increases
the magnification further still, and we see
something that resembles an imprint left by a
thumb. “That is exactly what it is”, explains Mr
Cotte. “You are looking at Leonardo’s thumbprint!”
The audience gives another collective gasp. But
there it is, unmistakable now: the imprint of
Leonardo da Vinci’s thumb. “Leonardo used to
smear paint very lightly with his fingers at this
stage of his career”, explains Mr Franck.
So 500 years after Leonardo used his thumb to
smooth the surface of paint depicting Cecilia
Gallerani’s chest, the use of that technique is
visible for the first time -- thanks to Pascal Cotte’s
camera.
But magnifying the surface to produce
extraordinary details is not the only thing that his
camera can do. . “And now I will highlight the
paint which was not put on by Leonardo,”
announces Mr Cotte in the manner of a
conjourer. We see an image with different
coloured patches, concentrated mostly at the
bottom and on the sides of Cecilia’s figure.
A brighter, cleaner, clearer image of The Lady
with the Ermine appears on the screen. “This is
how it would look if you took off the layer of
varnish, and re-touchings added in the centuries
after Leonardo”, Mr Cotte states. The background
has changed colour from black to blue. “All of the
background in this picture was added later,
possibly in the 19th century”, he explains.
“Leonardo would certainly have graded the
background”, points out Mr Franck. “He never
painted edges with sharp, ungraded contrasts of
the kind that are now visible in The Lady with the
Ermine between the sitter and the background
behind her. Leonardo always painted a series of
tones, with each tone blending into the other,
even when he was depicting the edge of a white
face against a dark background. That is part of
what gives his figures their extraordinarily realistic
look.”
Pascal Cotte smiles and nods in agreement. His
camera can’t yet paint like Leonardo – but it can
do a hell of a lot of the things, many of them of
inestimable importance to art historians and
restorers. A “virtual restoration”, in which you can
see what the painting would look like with the top
layer of varnish removed, but which does not
involve touching the original masterpiece itself at
all, is a tool of enormous value.
The whole thing seems to be a kind of magic.
What exactly is going on? How on earth does Mr
Cotte’s camera work?
“We used to take photographs”, he explains.
“Now we take measurements”. His camera can
take measurements of unprecedented precision:
its lens focuses light down to six microns – and if
you go any smaller than that, you run up against
the law of optical diffraction which means the
waves of light start interfering with each other.
The wavelength of the light reflected by each of
those minute points is then analysed and
measured by the camera. There are 240 million
such points in each scan the camera does of any
picture – and in order to capture the light from
every part of the spectrum accurately, the camera
scans each picture 13 times. The final image is
constructed from the data from all of those
billions of measurements. Its colours are
determined by an equation, devised by Mr Cotte,
which gives a numerical value for each pixel.
That value is the function of a series of variables,
including the kind of light the pigments are
viewed under, for pigments will reflect differently
under daylight than they do under candlelight or
fluorescent light, which is why paintings appear to
be made up of different colours in different lights.
The combination of the values generated each of
those pixels is what makes the image of the
painting produced by Mr Cotte’s camera – and it
is an image which can be magnified, with perfect
clarity, to show extraordinary details such as
Leonardo’s thumbprint.
In order to “take off” the painting’s varnish, Mr
Cotte devised a piece of software that calculates
the effect of varnish on the wavelength of light
reflected by each colour pigment used by
painters during the Renaissance. “That was very
difficult and laborious”, he explains. “It required
us to identify every pigment they used, take some
very detailed measurements, then compare the
wavelengths reflected by each pigment with light
reflected off a plain white surface covered with
the kind of varnish used by painters in the past,
aged appropriately by exposure to heat and ultraviolate light.”
At the end of that process, Mr Cotte was able to
subtract the effect of varnish on the wavelength
of light coming from each point focused by the
lens of his camera. That calculation produces an
image of a painting, such as Leonardo’s Lady
with the Ermine, with the varnish taken off.
Lumiere Technology – Press Release Sunday March 16th 2008
Jean Penicaut & Pascal Cotte are at Tefaf Maastricht – Stand 527 Business Pavillon
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“We can’t”, Mr Cotte says with due scholarly
caution, “say definitely that this represents the
final truth of how the picture would look without
varnish. We can only say that it is a much better
guide – that it is much closer to the truth – than
anything else.”
That much is indisputable -- and it is going to
have some momentous effects on the art world,
not least upon the way paintings are cleaned.
“For more than fifty years”, says Mike Daley, “an
argument has been raging about the merits of
restoration. This camera is going to settle that
argument. For the first time, we have an objective
way of seeing what a painting looks like
underneath the ‘later additions’ that the restorers
always want to clean off.”
The argument between restorers and their critics
has been heated and at times vitriolic, which is
not surprising considering that one side accuses
the other of destroying much of the heritage of
Western art. Restorers, at least in the AngloAmerican world of galleries and museums, have
insisted that everything they do is ‘scientific’, and
that they merely remove paint and varnish added
after the original master had finished or
abandoned his work. The most they ever do, they
say, is to take the picture back to the way it would
have looked when it left its original creator’s
studio.
The restorers’ critics – of whom Mr Daley is one –
have a rather different view of their work. The
critics say that restorers frequently destroy the
pictures they get their hands on. “Restorers in
Britain and America always say they’re ‘only’
taking off varnish”, maintains Mr Daley, “but only
too often, they take off far more than that, and
scrape or dissolve off the top layer of paint and
glaze as well.”
In common with other critics, Mr Daley charges
that restorers simply cannot tell where the varnish
added by later hands ends and the layers of
glaze and paint put on by the original artist begin,
for the two bond together over time. “When oil
paintings emerge from the hands of restorers”, he
asserts, “many of them have lost all the grace
and subtlety of the modelling of figures and
landscape, as well as the colour harmony. The
three-dimensional effects are gone. The result is
frequently flat, lifeless, dull – and in my view,
wrecked.”
He says examples are only too obvious in
London’s National Gallery. “Just take one look”,
he adds sadly, “at Bacchus and Ariadne, whose
surface has been scrubbed by restoration, and
compare it with The Worship of Venus and The
Adrians, both of which are in the Prado in
Madrid.”
Varnishing act: Titian's 'Bacchus and Ariadne' (left),
whose 'subtlety has been destroyed'; and his betterpreserved 'The Andrians'
All three pictures were painted by Titian, at the
same time and for the same room in the palace of
the Duke of Este of Ferrara. “But the National
Gallery’s Bacchus and Ariadne”, insists Mr Daley,
“has had ‘just’ the varnish taken off, while the
Prado’s The Worship of Venus and The Adrians
have not. Bacchus and Ariadne, post-restoration,
is now much brighter. But I defy anyone to fail to
notice how the colour harmony, the modelling
and the subtlety of the National Gallery’s Titian
has been destroyed. When it was shown next to
the Prado’s paintings in the Titian exhibition at
the National Gallery in 2003, the comparison was
shocking.”
Restorers counter that critics such as Mr Daley
do not understand the “science and technology”
of restoration. They can, they say, prove
scientifically that they only remove later repaintings, and never take off anything added by
the original artist: their critics, they insist, don’t
know what an ‘original’ painting would have
looked like, and are attached to versions of
Renaissance works (for instance) which are
covered in much later additions.
So who is right? The restorers or their critics?
Pascal Cotte’s camera has already begun to
provide critical evidence that will resolve the
matter. The Musee des Beaux Arts in Lille has a
painting of a mother with her child and baby,
probably by Hans Holbein the Younger.
Restorers decided the picture needed cleaning,
and got to work: they took off what they said was
merely “later varnish” from the baby. The restored
figure of that baby now looks very different to the
rest of the picture. The baby is full of bold pinks –
but the modelling is crude and crass, and the
baby seems flat and one dimensional in
comparison to the two other figures.
Lumiere Technology – Press Release Sunday March 16th 2008
Jean Penicaut & Pascal Cotte are at Tefaf Maastricht – Stand 527 Business Pavillon
3
Is the result of that restoration simply the
exposure of the reality of the painting that is
underneath the varnish? Or have the restorers
unwittingly removed some of the painted surface?
the internet to be able to call up images from the
camera. We hope to be able to provide, on line, a
secure data base of pictures we have
photographed.”
The image of the whole painting minus varnish,
produced by Mr Cotte’s camera, provides the
answer: it seems to show very clearly that the
restorers had stripped away some of the original
paint during their restoration. For the modelling of
the other figures underneath the varnish has,
according to the image created by the camera, all
the richness and three-dimensionality that the
restored baby so obviously lacks.
Restoration will not, however, be the only
discipline dramatically affected by Mr Cotte’s new
camera.
The image has already had an effect on the
Musee des Beaux Arts’ restoration policy. Alain
Tapie, the Chief Curator, took one look and
decided to halt the restoration of the Holbein
indefinitely. During the Last European Heritage
Day 2007 the half-restored picture was exhibited
in the Musee des Beaux Arts – and along side it
is the image from Pascal’s camera of what is
underneath the varnish in the rest of the painting.
The authentication of paintings and the
identification of fakes and copies is going to be
transformed as well. Every great artist had a
unique way of applying paint: each of them had
an idiosyncratic style of brush-stoke. But at
present, it is almost impossible to identify that
brush “signature”, at least at the level of detail at
which the human eye can see. By magnifying the
painted surface with such perfect accuracy, Mr
Cotte’s camera can make visible the brush
“signature” of each great artist. It should make it
possible to show, definitively, whether a painting
is by, say, Rembrandt or Raphael or Titian – or
whether it is not.
But that is in the future. For the moment, the
camera’s images simply inspire wonder and
astonishment. In Lumiere Technology’s office in
the Boulevard St Germain, we seem to be
looking, not at a reproduction of The Lady with
the Ermine, but at the original itself. The
revelation generated by Mr Cotte’s camera is
here now. As Mike Daley puts it, his jaw
dropping ever lower, 'It's a revolution... no,
it's a revelation and a revolution!'
Alasdair Palmer
www.lumiere-technology.com
Cleaning of Hans Holbein the Younger’s portrait has
left the baby looking one-dimensional (left); a digital
image of the original painting, underneath the varnish,
reveals a much richer picture
“If Pascal’s camera is used, as it should be, to
record images of paintings in collections around
the world”, maintains Mr Daley, “it will change the
way restoration is done, and may prevent much
of it from being done at all.” Museums and
galleries, he insists, will no longer be able to
claim that they alone “know” what a painting
looks like underneath what are alleged to be later
additions, and then assert that their own
restoration merely reflects that original state. Mr
Cotte’s camera will provide a publicly accessible,
objective image against which any museum or
gallery’s claim can be checked. As Jean
Penicaut, his partner at Lumiere Technology,
explains: “in future, you will only need access to
© Lumiere-technology & Palais des Beaux Arts de Lille
© Lumiere-technology and Princes Czartoryski
Foundation.
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the full copyright statement see Copyright
Link on Internet about this paper :
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08/03/16/sv_artcamera.xml
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Lumiere Technology
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Lumiere Technology – Press Release Sunday March 16th 2008
Jean Penicaut & Pascal Cotte are at Tefaf Maastricht – Stand 527 Business Pavillon
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